Java

Introduction to Java collection classes (re-learn)a . Collection (collection), map interface The two should be parallel relations. 　　1.MAP IntroductionThe map is stored as a key value (Key-value) pair, with 2 values. Use key to find value (ex:

Implement atoi to convert a string to an integer.Hint: Carefully consider all possible input cases. If you want a challenge, please don't see below and ask yourself what is the possible input cases.Notes: It is intended for the problem to be

Windows:Set Java_home: View JDK Installation pathJava-version: View JDK versionLinux:Whereis JavaWhich Java (Java execution path)Echo $JAVA _homeEcho $PATHTwo: Here are the environment variables for configuring Linux: (Remember source. bash_profile).

There are a lot of articles on the Internet to illustrate the performance of Java optimization of the good words are not lost C + +, and some are through some actual code testing to illustrate, but in some tests are obviously cheatingThis article is

Most of the reason is because the program does not close open resource connections, such as RMI, database, and other connections. It is also possible to have more than the default number of open files in Linux itself.First, start with the Linux

Experiment with familiarity with a Java development environmentFirst, the contents of the experiment1. Compiling and running a simple Java program using the JDK2. Edit, compile, run, and debug Java programs using EclipseSecond, the experimental

What is FilterFilter is a filter under Java that enables the filtering of Java Web Program clients and server-side messages, which can be pre-processed before the request is accepted by the servers, or before the client accepts response. The

Object access is ubiquitous in the Java language and is the most common program behavior, but even the simplest accesses involve the association between the three most important memory areas of the Java stack, the Java heap, and the method area , as

Java Virtual Machine Memory prototypeRegister: cannot be controlled in the programStack: A reference to a primitive type of data and objects, but the object itself is not stored in the stack, but is stored in the heapHeap: Storing data generated

First, data encapsulation1. The list collection is converted into JSON codeList List = new ArrayList ();List.add ("first");List.add ("second");Jsonarray jsonArray2 = jsonarray.fromobject (list);2. Map collection into JSON codemap map = new HashMap ()

First, the package1. Concept: To make member variables in a class private, but to provide the public method to access these member variables. This realizes the member variables in the hidden class, thus ensuring the security of the data;2.

Balanced binary trees can be unbalanced when inserting operations, and the AVL tree is a self-balancing two-fork tree.It re-balances the two-fork tree by rotating an unbalanced node, and the Find, insert, and delete operations are all O (log n) in

The four basic features of inheriting encapsulated polymorphic abstraction in JAVA Oo and being named Object-oriented programmingEncapsulation hides the internal implementation mechanism of the class so that it can change the internal structure of

Anonymous inner class is also an inner class without a nameBecause there is no name, the anonymous inner class can only be used once, and it is often used to simplify code writingBut there is also a precondition for using anonymous inner classes:

Java multithreading and java multithreading instances 1. multithreading Overview When a program runs, it may contain multiple sequential execution streams. Each sequential execution stream is a thread. It has the following advantages: It is easy

Reverse (reverse) of a single-chain table)The reverse order of a single-chain table is not part of the algorithm. What can we do with our friends? the chance of an interview is high, so we put it together with the algorithm. About the basic

Implementation of java multithreading and thread poolJava implements multithreading in three ways: Inheriting the Thread class, implementing the runnable interface, and using ExecutorService, Callable, and Future to implement multithreading with

ACM competition Java programming summary, acm competition java programming 1. String Length String str = new String ("abcd "); Int length = str. length (); 2. Length of the array2.1 For a [] [] a. length represents the number of rows of a [I].

Quick recall Regular Expression This is not an entry-level article, but if you have an understanding of regular expressions or have used them, it can help you quickly recall them. Reading this article requires you to have used regular expressions or

Several common Java Regular Expressions (search index, match, and replace) A regular expression is a rule agreed upon to facilitate string operations. many mainstream languages such as PHP and JAVA have regular expressions. the most common method is